Causes of Crohn's Disease

The causes of Crohn's disease are unknown and no theory is definitive. The genetic influence is very important and approximately 20% of the patients have relatives affected by this disorder; it can be said that the most important risk factor for developing an inflammatory bowel disease is to have a family member who suffers from the disease. At least three mutations of the NOD2 / CARD15 gene, which is specific for Crohn's disease, have been identified and which determine an altered response to bacteria of what is called the intestinal microbiota (the large variety of bacterial species that inhabit the intestine).

The affected people have an immune system that reacts exaggeratedly to viruses or bacteria that reach the intestine, causing the inflammatory reaction of the entire thickness of the intestinal walls, where they form scars. What has not yet been identified is whether some kind of microorganism is more directly involved than another.

On the other hand, smoking has been shown to increase the risk of developing Crohn's disease, and it also worsens the course of the disease if smoking continues. In fact in some siblings with inflammatory bowel disease, there is the curious circumstance that the smoker presents Crohn's disease and non-smoker ulcerative colitis.

Other factors that negatively influence the disease are daily stress and important life events such as loss of a loved one, a divorce, or interpersonal conflicts, more in the activity of the disease than in its appearance.